Drag Strip tips and advice needed.

Yes Sir you definitely needed to get a bung welded to your exhaust ! Then you can screw the sensor into the bung !! You can’t have unmetered air coming in !! The O2 will read lean and tell the computer to fatten up the system ! That maybe your problem !! You get lean codes every time ! Does your fuel injection have a mass air meter or a map sensor ? I’m not familiar these after market fuel injection systems